Method and appartus for seam forming

ABSTRACT

A method of forming a seam joining two workpieces, such as thermoplastic shoe parts, by supporting said parts with the edges to be seamed in adjacent relationship on a support surface having a grooved-out portion aligned with the edges to be seamed, forming a weld along said adjacent edges, flowing a portion of the weldment into the grooved-out portion during welding, thereby forming a reinforcing rib aligned with and superimposed over the seam joining said workpieces and apparatus for use in practising the method.

I Unlted States Patent 1151 3,643,27 1

Wilkinson 1 1 Feb. 22, 1972 [54] METHOD AND APPARTUS FOR SEAM [56] References Cited FORMING UNITED STATES PATENTS [72] Inventor: Lionel W. Wilkin on, N r g 2,983,932 5/1961 Clason ..12/142 E gland 3,076,212 2/1963 Vachon ..l2/l46 C [73] Assigneez USM Corporation, Flemmgton, NJ. Primary Examiner patrick D Lawson [22] Filed: Aug. 24, 1970 Att0rney-Richard A. Wise, Richard E1. Megley and Howard 1 pp No: 669446 R. Berkenstock, Jr.

57 ABSTRACT [30] Foreign Applicafion Priority Data A method of forming a seam joining two workpieces, such as Sept. 11,1969 Great Britain ..44,907/69 thermoplastic shoe parts, y supporting Said parts with the edges to be seamed in adjacent relationship on a support 5ur- 521 US. Cl. ..12/146 c, 12/52 face having aligned with the edges be [511 1111.131. ..A43d 11/00 Seamed fmming a weld Said adjacent edges Wing a 58 Field of Search ..12/142 R 142 E 52 59.5 Ponion 0f weldmem during l2/l R, 146 R, 146 C; 112/62 welding, thereby forming a reinforcing rib aligned with and superimposed over the seam joining said workpieces and apparatus for use in practising the method.

6 Claims, 6 Drawing Figures METHOD AND APPARTUS FOR SEAM FORMING BACKGROUND OF THE INVENTION In the manufacture of a shoe, and by the word shoe is meant outer footwear generally whether completed or in the process of manufacture, it is customary to form an upper which is later lasted and attached to a sole. The upper is generally formed from pieces of sheet material, such as leather or fabric, which are secured together as by stitching to provide an upper of the desired shape. Generally, in the forming of an upper, two portions of material forming the quarter of the shoe are joined together in a back seam, which in the completed shoe extends down the back ofthe heel end portion of the upper. It is usual for the back seam to be formed by stitching the two quarter portions together. From the foregoing it is apparent that both manual skill and time are required to provide a back seam which is strong and of pleasing appearance.

With the advent of plastic and similar heat sealable materials for use as shoe upper components, it has become possible to form the back seams by means other than the conventional method of stitching. Previously issued U.S. Pat. No. 3,376,594, issued Apr. 9, 1968, and application Ser. No. 857,516 now US. Pat. No. 3,545,022 filed Sept. 12, 1969, illustrate apparatus for forming a back seam in heat or pressure sealable shoe upper components. While a back seam formed with this apparatus (being a plain butt joint type of construction) is sufficient to withstand the various strains subsequently imposed upon the upper during the various manufacturing steps, it has sometimes been found, and especially in cases in which insufficient care has been taken by the wearer in putting on the shoe, that the back seam portion of the shoe is susceptible to breakdown, generally at the top. Further, while the plain butt joint type of back seam may be appealing to the eye by virtue of its simplicity and smooth appearance, it may be desirable to provide a more conspicuous back seam, perhaps as a fashion feature.

SUMMARY OF THE INVENTION It is an object of this invention to provide an improved method and apparatus for forming a seam joining two workpieces as, for example, a back seam in a shoe upper comprised at least in part of thermoplastic materials by welding the parts together in such manner that the seam thus formed is of greater thickness than the adjacent portions of the upper, thereby producing a strong back seam which may enhance the appearance of the shoe.

To this end and in accordance with a feature of the invention, the seam is formed by clamping the parts to be joined with edge portions in alignment with each other and the surfaces adjacent said portions abutting each other, between two pressing members of appropriate complemental shapes, one of which members has a groove in alignment with the abutting edge portions, and applying heat to the edge portions whereby they are welded together, a portion of the thermoplastic materials flowing into the groove so that the finished seam is ribbed, thus imparting great strength to the seam.

The rib will preferably lie in the exterior surface of the shoe or workpiece. In accordance with a further feature of the invention, the surfaces of the groove may be formed to provide a decorative effect to the rib along the seam. A member, such as a serrated wire, may be located within the groove to provide this decorative effect.

These and other features of the invention will now be described by reference to the drawings and pointed out in the claims.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view partially cut away of apparatus employing my invention;

FIG. 2 is a perspective view of a support member of the apparatus of FIG. 1;

FIG. 3 is an elevational, partially sectioned view of the two support members of the apparatus of FIG. I;

FIG. 4 is a section along the line IVIV of FIG. 3;

FIG. 5 is a view similar to FIG. 4 of an alternative embodiment of the invention; and

FIG. 6 is a pictorial view of the ribbed seam producedby my improved method and apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT It will be understood that the apparatus embodying the in vention is shown by way of illustration only and not by limitation thereof. The illustrative apparatus which is particularly adapted for forming the curved back seam between two quarter portions of a shoe upper is generally shown in Fig. I and is further described and illustrated in application Ser. No. 857,5l6 filed Sept. 12, 1969, and similarly described and illustrated in U.S. Pat. No. 3,376,594. The apparatus generally comprises at least one operating head 2 provided with work handling means 4 and 6 for receiving and clamping two portions of sheet material 8 and 10, which in the illustrated embodiment are the two shoe upper quarter portions. The work handling means 4 and 6 are capable of receiving the two portions of sheet material 8 and I0 and clamping them with the edge portions 12 and 14 thereof adjacent to each other, generally with the surface portions thereof adjacent the edge portions in contact with one another for orienting the portions 12 and 14 in general abutting relationship. It is also to be appreciated as part of the invention that the quarters 8 and 10 may be placed adjacently with the edges 12 and 14 slightly overlapping, more explicitly explained subsequently. The apparatus further includes joining means including a support member 16 having a forming surface thereon which in the preferred embodiment is defined by two angularly disposed curved surfaces 18 and 20.

As further illustrated in FIGS. 2, 3 and 4, in the preferred embodiment, the curved surfaces 18 and 20 meet in an imaginary vertex 21 being a curved line which falls in a plane about which the member 16 is symmetrical and defining the centerline of a grooved-out portion 22 or channel in which a reinforcing rib may be formed. In the illustrated embodiment, the curved forming surfaces 18 and 20 are particylindrical and the axes thereof are arranged at right angles to one another. Further, the grooved-out portion 22 is illustrated as rectangular in cross section and extending along a curve in the central longitudinal plane of the support member 16.

The walls 28 of the groove 22 may be smooth so that a plain rib is formed when the shoe quarters l8 and 20 are joined and ribbed. Alternatively, a decorative surface may be provided on walls 28, e.g., lines and serrations. Such decorative surfaces may be provided in the grooved walls themselves or a member having a decorative surface such as a serrated wire may be secured in the groove. Likewise, the cross section of the groove may be ofthe illustrated rectangular shape or any desired shape such as semicircular.

Cooperable with the support member 16 is a pressing member 24 of a complementary shape to the form member 16. The pressing member 24 is attached to lowering means 26 to engage the shoe quarter material 8 and 10 when lowered. In the illustrated embodiment of the apparatus disclosed, the member 16 and the pressing member 24 are of a conductive material such as aluminum or other suitable electrode material so that a high-energy electric field may be generated therebetween by means operative therewith (not shown).

FIG. 5 illustrates an alternative embodiment whereby the ribbed portion may be formed on the reverse side of the seamed members. This embodiment includes a grooved out portion 30' in the presser member 24' with the support member 16 exhibiting continuous surfaces 18 and 20' meeting in a true vertex 2I'. Implied as well, is an embodiment which would include grooved-out portions such as 22 and 30 in both support member 16 and presser member 24.

In using the illustrative apparatus for joining the two quarter portions 8 and 10 of a shoe upper to form a back seam therebetween, the quarter portions 8 and 10 would be carried by the handling means 4 and 6 to the surfaces 18 and 20 of the support member 16 and positioned with the edges 12 and 14 in either abutting or slightly overlapping relationship and extending along the groove 22.

Where a substantial amount of material is required to fill the grooved-out portion in making a rib, the slight overlap of edges 12 and 14 may be necessary to prevent undesirable robbing of material adjacent the seam. As an alternative, supplemental material may be added externally as by laying a supplementary strip of thermoplastic material in the groove 22 prior to placing the quarter portions 8 and 10 thereover.

The portions 8 and 10 are clamped in the predetermined abutting or overlapping relationship, by the pressing member 24 which is then lowered by means 26 and pressure is applied over the area of the surfaces 18 and with the portions 8 and 10 therebetween. Heat may be applied via the members 16 and 24 to form a welded seam 32 of the quarter portions 8 and 10 at their juxtaposed edges 12 and 14 forming a distinctive rib 34 as illustrated in FIG. 6. In addition, the support member 16 and the pressing member 24 may act as electrodes between which a high-frequency electric field (e.g., an RF field) may be created to facilitate the fusion of the edges 12 and 14 into a thermally welded seam. If preferred, the quarter portions may be heated by conventional means such as conductive heating elements installed in the member 16 and the pressing member 24.

When the quarter portions 8 and 10 are joined by the previously illustrated method, the conditions of heat and pressure applied by the aforementioned means causes the ther moplastic material of the quarter portions 8 and 10 to flow into and fill the groove 22 to form a homogeneous pool and bond when the pool cools and solidifies, thereby joining the quarter portions into a single member. In this way the back seam 32 is produced with a reinforcing rib 34 integral with the seam having a conspicuous appearance with a surface texture depending upon the texture or pattern of the groove 22. It will be thus appreciated by those familiar with the art that the back seam thus produced with a reinforcing rib may be of sturdier construction than a nonribbed seam. It will be further appreciated that the joined quarter portions may be of a variety of materials such as fabric material coated with conventional polyvinyl chloride plastic material or materials such as the thermoplastic poromeric materials, so long as the materials are capable of being welded together.

The principles and features of this invention may be utilized and varied in numerous embodiments and applications without departing from the scope of the invention.

Having thus described the invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. ln apparatus for forming a seam by welding the edges of two workpieces, such as thermoplastic shoe parts, including a support member, a presser member movable to a position adjacent said support member to clamp said pieces to be seamed, and orienting means for locating said workpieces in precise position on said support member with the edges to be seamed in adjacent relation, the improvement comprising a forming surface disposed on at least one of said support member and presser member adapted to receive said workpieces to be seamed, said forming surface having a groovedout portion defining a longitudinal channel aligned with the seam to be formed and means for welding said workpieces on said forming surface along said channel to scam said workpieces whereby the weldment will fill said channel to form a reinforced seam of substantially greater thickness than that of the adjacent portions of said seamed workpieces.

2. The apparatus according to claim 1 wherein the surface of said longitudinal groove is embossed with a decorative pattern whereby said surface will impart a complementary pattern to the seam formed therein.

3. The apparatus according to claim 1 wherein said means for welding includes means for creating a high energy electric field between said forming surface and said presser member.

4. The apparatus according to claim 3 particularly adapted for the formation of a back seam between two shoe upper quarters wherein sard formrng surface 15 drsposed on sard support member and comprises two angularly disposed curved surfaces meeting in a salient angle, and said grooved-out portion defines a curvilinear channel coextensive with the vertex of said angle.

5. A method of forming a seam between two workpieces such as thermoplastic shoe parts comprising: orienting said parts with edges to be seamed in adjacent relationship; supporting said workpieces on a support surface having a grooved-out portion aligned with the edges to be seamed; forming a weld along said adjacent edges of said workpieces and deflecting a portion of said weldment into said channel during welding thereby forming a ribbed seam of substantially greater thickness than the thickness of the workpieces adjacent said seam.

6. A method according to claim 5 particularly adapted to closing the back seam of two quarter portions of a shoe upper including supporting said quarters on angularly disposed curved surfaces of said support surface meeting in a curvilinear channel, clamping said quarters on said support surface by pressing means, welding said quarters along said channel by passing a high-energy electric field between said support surface and said pressing means and deflecting a portion of said weldment into said channel during welding, thereby forming a curvilinear rib aligned with the seam joining said quarters. 

1. In apparatus for forming a seam by welding the edges of two workpieces, such as thermoplastic shoe parts, including a support member, a presser member movable to a position adjacent said support member to clamp said pieces to be seamed, and orienting means for locating said workpieces in precise position on said support member with the edges to be seamed in adjacent relation, the improvement comprising a forming surface disposed on at least one of said support member and presser member adapted to receive said workpieces to be seamed, said forming surface having a grooved-out portion defining a longitudinal channel aligned with the seam to be formed and means for welding said workpieces on said forming surface along said channel to seam said workpieces whereby the weldment will fill said channel to form a reinforced seam of substantially greater thickness than that of the adjacent portions of said seamed workpieces.
 2. The apparatus according to claim 1 wherein the surface of said longitudinal groove is embossed with a decorative pattern whereby said surface will impart a complementary pattern to the seam formed therein.
 3. The apparatus according to claim 1 wherein said means for welding includes means for creating a high energy electric field between said forming surface and said presser member.
 4. The apparatus according to claim 3 particularly adapted for the formation of a back seam between two shoe upper quarters wherein said forming surface is disposed on said support member and comprises two angularly disposed curved surfaces meeting in a salient angle, and said grooved-out portion defines a curvilinear channel coextensive with the vertex of said angle.
 5. A method of forming a seam between two workpieces such as thermoplastic shoe parts comprising: orienting said parts with edges to be seamed in adjacent relationship; supporting said workpieces on a support surface having a grooved-out portion aligned with the edges to be seamed; forming a weld along said adjacent edges of said workpieces and deflecting a portion of said weldment into said channel during welding thereby forming a ribbed seam of substantially greater thickness than the thickness of the workpieces adjacent said seam.
 6. A method according to claim 5 particularly adapted to closing the back seam of two quarter portions of a shoe upper including supporting said quarters on angularly disposed curved surfaces of said support surface meeting in a curvilinear channel, clamping said quarters on said support surface by pressing means, welding said quarters along said channel by passing a high-energy electric field between said support surface and said pressing means and deflecting a portion of said weldment into said channel during welding, thereby forming a curvilinear rib aligned with the seam joining said quarters. 